Joint Transceiver Optimization for MIMO Multiuser Relaying Networks with Channel Uncertainties

This paper addresses the problem of amplify-and- forward (AF) relaying for multiple-input multiple-output (MIMO) multiuser relay networks. where each source transmits multiple data streams to its corresponding destination with the assistance of multiple relays. Assuming only imperfect channel state information (CSI) of all the source-relay and relay-destination links, we propose a robust approach to jointly design the source and relay precoders and the receive filters, in which the worst per-stream mean square error (MSE) is minimized subject to source and relay power constraints. The channel uncertainties are assumed to be Gaussian distributed and the well-known Kronecker model is employed to characterize the spatial correlations in the proposed design. The resultant optimization problem is nonconvex and therefore, an algorithmic solution with proven convergence is proposed by resorting to the iterative block coordinate update approach along with matrix transformation and convex conic optimization techniques. Simulation results show that the proposed joint transceiver design can achieve an improved robustness against the channel uncertainties when compared to the non-robust approaches.